Apparatus for producing bifocal lenses.



No. 836,486. PATENTED NOV. 20, 1906. C. W. GONNEB.

APPARATUS FOR PRODUCING BIPOGAL LENSES.

APPLICATION FILED APE.21.1903.

3 SHEETSSHET l @mmwfoz Charles W. Conner No. 836,486. PATENTED NOV. 20,1906.

3 SHEETS-SHEET 2.

VII/IA- b I I 3 Mmufoc W'LtMQ/JWO 7% Charles W. Conner W I F;

I My k g No. 836,486. 7 PATENTED NOV. 20, 1906.

G. W. BONNER. APPARATUS FOR PRODUCING BIFOGAL LENSES.

APPLICATION FILED APR. 2 1. 1903.

3 SHEETS SHEET 3- Charles W. Conner nmnnsmms A E T- orFIo E.

GHARLES'W.. GQNNEE, OF INDIANAPOLIS, INDIANA.

APPARAT US FOR PRO DU CI NG'BI FO CAL LENSES.

Specification of Letters Patent.

Patented Nov. 20, 1906.

Application filed April 21, 1903- Serial No. 153.696.

To all whom it may concern? Be it known that I, CHARLES W. CONNER acitizen of the United States, residing at Indianapolis, in the county ofMarion and State of Indiana, have invented certain new and usefulImprovements in Apparatus for Producing Bifocal Lenses, of which thefollowing is a specification. The object of my invention is to providean apparatus for grinding from a single piece of crystal simultaneouslythe two surfaces of a bifocal lens, said surfaces being of differentdioptrics and the line of junction between, the two focal surfaces beingpractically even,

smooth, and invisible.

In carrying out said invention I prov1de a crystal-holding member, arotary grinding.

member cooperatin therewith and having a spherically-disposegrinding-surface, and anadj acent non-spherically disposedgrindingsurface which has the same degree 0 ferential curvature in onedirection as the spherically-disposed surface, and means for revolvingone of said members that. is, either the crystal-holding member may bestationary and the rotary grinding memberrevoluble and rotary or saidgrinding member may be only rotary and the crystal-holding apparatus forusing the same; Fig. 2, a plan so that it will not serve asagrinding-su'face. I

thereof; Fig. 3, a vertical section of the apparatus for finishing oneof the surfaces; Fig. 1, a plan thereof. Figs. 5, 6, 7, 8, and 9 areviews of several forms which my improved grinding-wheel may assume, eachof said figures giving also a transverse section of the whole lensformed by such wheel, together with a similar section of thelens whenused for eyeglasses or spectacles. Fig.'. 10 is a diagramof the lensshown in Fig. 6-. Fig. 11 is an elevation of a grinding-wheel in whichthe intermediate portion is sufiiciently depressed circum- In Figs. 1and 2, 15 indicates a ing-Wheel the intermediate periphera portion 16 ofwhich is parallel with the axis of rotation, while the edge portions 1717 are convex. Wheel 15 is mounted upon the arbor 18 and rotated b meansof a pulley 19. Mounted above whee 15, preferably but not necessarily atright angles to arbor 18, is a lens-rot ating arbor 20, journaled in asuitable bracket 21, which is adjustable along a line substantiallyparallel with the axis of arbor 18 by any suitable means, such as anadjusting-screw 22. Arbor 20 is rotated preferably at a considerablyhigher speed than arbor 18 by means of a pulley 23 and belt 24 whichbelt passes around idlers 25 anda drivingwheel 26, carried by arbor 18.

Arbor 20 is capable of vertical movement within its bearing-bracket 2 1toward and from theperiphery, of the grinding-wheel 15 and is,

normally forced downward b a spring 27. The arbor 20 may be held in itsupper position by means of a sleeve mounted within the bearing ofbracket 21 and provided with a pin 28, projecting throughabayonet-slot29.

In operation the lower end of arbor 20 is adapted to enga e and rotatethe lens-holding head 30, to which a crystal 31 is attached in the usualmanner. The crystal 31 may preferably be roughed out, so as to partiallyconform with the curvature of the grindingsurfaces 17, by the ordinarygrinding means, whichneed notbe here described. After the head 30,together with its attached crystal 31, has been connected to arbor 26 itis held in engagement with the periphery of the grinding-Wheel 15 byspring 27 and the parts then rotated, the grinding-wheel about its arbor18 and the crystal 31 about the axis of arbor 20. The grinding-surfaceidoperates I to ro'ducea central lens-surface concentric witi the arbor 20and the grindingsurfaces 17 17 simultaneously operate to produce alens-surface concentric with arbor 20 and surrounding the lens-surfaceproduced by the grinding surface 16. o' I If desired, the twolens-surfaces may be ground and finished by the same or similar wheels;but in practice I find that this-may result in an imperfect centrallens-surface,for the reason that slight irregularities in the surface16, especially in a line directly beneath or very closely beneath theaxis of arbor 20,

may possibly produce concentric ridges and hollows in the lens-sm face.For the reason after the crystal 31 has been roughed out by the wheelsuch as shown in Fig. 1, where the surfaces 16 and 17 17 havesubstantially the pro er dioptrics for the two desired surfaces,IPremove said wheel and substitute therefor a wheel such as that shownin "Fig. 11, where: the intermediate grinding-surface is removed, as atb, and grindin is continued until a slight surplus of materia is left inthe center of the crystal, as shown in Fig. 3. The external-surface isfinished with a wheel similar to the wheel shown in Fig. 11 on by anydther desired means, and the crystal is then transferred to the rotatinghead 32 (shown in 3) and there rotatedi'n conjunction with agrinding-plate 33, the under face of which has been given the roperdioptric cur-ve desired for the centraFsurface, and the surplus materialof the center of the crystal is then reduced" by this grinder until theline of junction between the central surface and the surrounding surfaceis made practically invisible.

The grinding-plate 33 is of less diameter than the lens-surface which itis to grind and finish,

so that as it is moved transversely of the crystal across its centerbythe arm 34 it will be rotated upon the pin 35' as an axis by reason ofthe rotation of the crystal 31 by head 32.

In Fig. 5 I have shown a ortion of the periphery of a grinding-wheehaving a pair of separated grinding-surfaces 40, which are of the samedioptric, and an intermediate grinding-surface 41 which isarallel withthe axis of rotation. Such a w eel will produce a lens such as shown inFig. 5, withaflat central circular surface 41. The finishedeyeglass-lens is also shown in the same figure, a portion of the crystalhaving-been removed, so as to bring the surface 41 to one edge of thefinished lens. I s

In Fig. 6 the surfaces 42 42 are of a plus dioptric which is greaterthan the plus dloptrio of the intermediate surface 43. This will producea lens having a, central fiat circular portion 47 and a surrounding plussurface 46 Attention is called to the fact that the grinding-surfaces-17 in Fig. 1 are spherically disposedthat is, all parts of saidgrindingsurfaces have one common center. The effect ofthis is to give tothe crystal in the latter art of the operation the desired sphericalsurace andin a erfect form,all parts of the major surface 0 the crystalengaging the. grind- 6 5 ing-tool. I The intermediate grinding-surface16 has the same degree of curvature circum-' ferentially as thegrinding-surfaces 17; but transversely of the wheel 15 the surface 16 is.not s herical, but is formed so as to produce the esired minor surface,either plano', concave, or convex.

\ In Fig. 9 the grinding-surfaces 48 48 are minus and the intermediategrinding-surface 49 minus of a eater dioptrlc, thus roducing a lenshaving an intermediate p us surface 49 and a surrounding plus surface48.

In Fig. 10 I have shown the eyeglass-lens illustrated in Fig. 6 and havefurther shown that the radius a is common to both of the lens-surfaces42 and 43. v

It will be readily understoodthat, if desired, one'of thegrinding-surfaces 17 17 may be omitted, or, if desired, a singlegrindingsurface oflset with relation to the arbor'20- the external ormay be used for producin %ut both of these surrounding lens-surface;

changes would probably prove to be objec-' formed may be-and usuallywill be given any desiredd-ioptric conformation in any desired manner.

After the crystal has been provided on one face with the two surfacesand the opposite I face reduced to the desired conformatlon an eyeglassor spectacle lens is produced by removing a portion of the outer orsurrounding surface, so that the central surface will then lie at thelower edgeof the finished lens. is thus ossible to produce from a singlecrystal a bi ocal lens with the near-vision" por-' tion roperlypositioned at the lower edge.

I c aim as my invention 1. Apparatus for roducin bifocal lensesincluding a rotary ho der for t e lens-crystal,

and means for two bifocal surfaces of different dio tricsslmultaneousl-y on one I face thereof, su stantially as set forth. I

2. Apparatus for producm bifocal lenses including a rotary crystal-hoder, and .a; ro-

tary and aving a spherically-disposed annular grinding-surface and anadjacent non-sphergrinding member cooperating therewith i icallydisposed annular grinding surface which has the same degree ofcircumferential curvature as the s herically-dis 'osed surface.

3-. Apparatus or producin ifocal lenses including a rotary crystal-hoder, and a rotar-y grinding member cooperating therewith.

and having a spherically-disposed annular grinding-surface and anadjacent non-spherically-disposed annul argrinding-surface which has thesame degree of. circumferential ourvature as the spherically-disposedsurface, the axis of said crystal-holder beingin line with a radiusthrough the center of the nonspherical surface of the grindin member.

4. Apparatus for producing Iufocal lenses including a crystal-holdingmember, a grinding member having two parallel sphericallydisposedannular grinding-surfaces and an intermediate non-spherically-disposedannular grinding-surface which has the same degree of circumferentialcurvature as the sphericallyalisposed surface, and means for causing agrinding movement between said members.

5. In an apparatus for producing bifocal lenses, the combination of agrinding element having a plurality ofgrinding-surfaces thereon ofdifferent dioptr1cs,-whereby focal surfaces of different dioptrics aresimultane- 1 ously produced upon the lens-crystal, means for rotatingsaid grinding element, a holder for the lens-crystal, and means formoving said crystal-holder with relation to the surface of said grindingelement.

6. In an apparatus for producing bifocal a grinding element -having aplurality of grinding-surfaces thereon of different dioptrics, wherebyfocal surfaces of different dioptrics are simultaneously produced uponthe lens-crystal, means for rotating said grinding element, a holder forthe lens-crystal rotatable about an axis at an angle to the axis of therinding ele-' ment and offset from the grindmg element, and means forrotating the crystal-holder. 7. In an apparatus of the class described,the combination of a pair of separated grinding-surfaces of the samedioptric, a crystalholder, means for rotating said crystal-holder uponan aXis at an angle to the grinding-surfaces, and means for causing arelative movement between the grinding-surfaces and the crystal-holderalong the line of separation of the two grinding-surfaces.

In witness whereof I have hereunto set my hand and seal, atIndianapolis, Indiana, this Witnesses:

ARTHUR M. H001), JAMES A. WALSH.

